Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 261944
Area Forecast Discussion
National Weather Service Charleston SC
344 PM EDT Sun Mar 26 2017
...INCREASED RISK FOR RIP CURRENTS THROUGH MID-WEEK...
Atlantic high pressure will weaken early this week. A weak cold
front will stall over the area during the middle of the week,
then shift back north as a warm front Friday. Another cold front
should move through Saturday or Saturday night followed by
drier high pressure Sunday.
.NEAR TERM /THROUGH TONIGHT/...
Through sunset: Low-level convergence near the sea breeze coupled
with the tail end of lingering shortwave energy moving into
North Carolina has been enough to support a small line of
broken, mostly light showers across the interior this
afternoon. KCLX reflectivity data indicate the updrafts embedded
within this activity are struggling with the presence of a
potent subsidence inversion. Will reintroduce pops across
portions of interior Southeast South Carolina through late
afternoon to cover. Only expect a hundredth or two to fall where
heavier downpours occur.
Tonight: After dampening slightly in the wake of weak shortwave
energy, mid/upper-level subtropical ridging will rebuild over
the area tonight as Atlantic high pressure holds firm. Expect
dry conditions to prevail through daybreak with lows dropping
into the mid-upper 50s inland with lower 60s at the beaches.
Could see some patchy, mainly shallow ground fog develop early
Monday prior to the arrival of a thicker cirrus canopy. The
better chances for fog will be across interior Southeast
Georgia, but no major impacts are expected.
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Monday and Tuesday: Weak isentropic lift ahead of a low pressure
system passing to the north will help produce some cloud cover as
moisture deepens over the Southeast. However, a light onshore flow
will gradually veer to southwest through Tuesday, suggesting warm
temps well ahead of a cold front approaching from the northwest. In
general, afternoon temps will peak in the lower 80s each day away
from the coast. Temps should be warmer on Tuesday as the southwest
sfc wind and partial downsloping wind aloft hold the seabreeze to
the coast for a longer period than that on Monday. Given these temps
and increasing levels of moisture, a slight chance to chance of
showers will remain in the forecast. A few thunderstorms will also
be possible during peak heating, mainly inland on Monday and in
northern locations Tuesday where instability levels and mid lvl
forcing associated with a h5 shortwave are greatest. Overnight lows
will remain mild Monday and Tuesday nights. In general, temps will
only dip into the upper 50s and lower 60s.
Wednesday: A dry cold front will approach from the northwest well
after its parent low shifts off the Mid-Atlantic and Northeast
coast. The amount of separation between the front and the parent low
suggests the front will stall over or near the area while it becomes
aligned parallel to the mid/upper lvl flow. Ahead of the front,
temps will remain considerably warm under a mid/upper lvl ridge of
high pressure building aloft. In general, temps should peak in the
low/mid 80s away from the immediate coast.
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
The stalled front should shift north as a warm front Friday followed
by a cold frontal passage Saturday or Saturday night. Drier high
pressure should then return later in the weekend. Showers and
thunderstorms will be possible, mainly Thursday through Friday
night, with temperatures running above normal through at least
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR. Might see some shallow ground fog at both terminals just
before sunrise, but no impacts are anticipated.
Extended Aviation Outlook: Mainly VFR. Brief flight restrictions are
possible each afternoon with showers and/or thunderstorms this week,
best chances Thursday or Friday. Low probability of restrictions due
to early morning low clouds and/or fog.
Tonight: South to southeast winds will persist as Atlantic high
pressure remains well offshore. Speeds will remain 10 kt or less
with seas 2-4 ft nearshore waters and 4-5 ft offshore waters.
Monday through Friday: Winds/seas are expected to remain below Small
Craft Advisory levels as high pressure slowly weakens ahead of weak
cold front arriving from the northwest Wednesday. However, winds
should peak near 15-20 kt at times Tuesday ahead of the front while
seas build up to 3-5 ft, highest in offshore Georgia waters. The
front will transition into a warm front as it moves back north
Friday. Seas could reach 6 feet near the Gulf Stream through Tuesday
due to swells from low pressure well offshore. Advisories will be
possible across the outer GA waters through Tuesday and then for
more of the area Thursday night/Friday as strengthening southerly
winds build seas to 6 feet again.
Rip Currents: A Moderate Risk of rip currents is in the forecast
along all beaches Monday due to long period swell of 2-3 seconds
from the southeast coinciding with the upcoming new moon. The
combination of long period swells, astronomical influences and
onshore winds will support an enhanced risk for rip currents through